Fail-safe throttle for an internal combustion engine

ABSTRACT

A throttle for an internal combustion engine having a first spring which tends to return the throttle into the idle position and against the force exerted by the operator. The throttle is provided with at least a second spring interconnected to the first spring by an arrangement so that if the first spring breaks the interconnection arrangement releases the second spring which is now able to return the throttle into the idle position.

C United States Patent 1 [111 3,

Klemm et al. Dec. 9, 1975 [54] FAIL-SAFE THROTTLE FOR AN INTERNAL 3,698,372 10/1972 Eshelman 123/198 D X COMBUSTION ENGINE 3,699,943 10/1972 Eshelman.... 123/198 D X 3,704,635 12/1972 Eshelman 123/198 D X Inventorsr Peter m Wolfsburg; Klaus 3,731,667 5/1973 MacMillan 123/198 DB Schulze, Hondelage, both of 3,760,786 9/1973 Marsh 123/198 DB Germany 3,830,213 8/1974 Herman 123/198 DB [73] Assignee: Volkswagenwerk Aktieng esellschaft,

Wolfsburg, Germany Primary ExaminerCharles J. Myhre Assistant Examiner-William C. Anderson [22] Filed 1974 Attorney, Agent, or Firm-Ernest F. Marmorek [21] Appl. No.: 430,777

[30] Foreign Application Priority Data [57] ABS CT Jan. 12, 1973 Germany 2301449 A throttle for an internal combustion engine having a first spring which tends to return the throttle into the [52] US. Cl 123/ 198 D; 123/198 DB idle position and against the force exerted by the oper- [51] Int. Cl. F02B 77/00 ator. The throttle is provided with at least a second [58] Field of Search 123/98 R, 198 D, 198 DB, spring interconnected to the first spring by an arrange- 123/142; 74/482, 513, 470; 251/67; 180/82 ment so that if the first spring breaks the interconnection arrangement releases the second spring which is [56] References Cited now able to return the throttle into the idle position.

UNITED STATES PATENTS MacMillan 123/198 DB 7 Claims, 6 Drawing Figures US. Patent Dec. 9, 1975 Sheet 1of3 3,924,596

US. Patent Dec. 9, 1975 Sheet 2 of3 3,924,596

US. Patent Dec. 9', 1975 Sheet 3 of3 3,924,596

air

Fig.5

FAIL-SAFE THROTTLE FOR AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION This invention relates to a throttle for an internal combustion engine and particularly for a throttle for an automobile having an air intake manifold or vacuum tube.

Usually the throttle of an automobile which is disposed in the air intake manifold is provided'with a first spring which tends to urge the throttle into the idle position against the force exerted by the operator. This force is usually exerted by means of a pedal. If the spring of such a throttle breaks, the throttle is not returned to the idle position so that the engine may run at a large number of revolutions contrary to the wishes of the operator. Particularly for automobiles, this is intolerable because it may cause accidents. For this reason an American safety regulation provides that there must be two energy sources so that even if one of the energy sources fails, for example, due to breakage of the first spring the throttle is safely returned to the idle position in the absence of contrary signals from the operator.

It would, of course, be feasible to realize this principle of utilizing two energy sources by the provision of two parallel springs. However, such an arrangement of two springs in parallel would require larger operating forces for moving the throttle from the idle position because the throttle must be returned into its idle position within a predetermined time. Both springs must have relatively large forces.

It is accordingly an object of the present invention to provide a throttle of the type discussed which is provided with means to prevent failure of the throttle when the first spring is broken, but which does not have the disadvantage of an undesired increase of the necessary operating force.

SUMMARY OF THE INVENTION The solution of this problem in accordance with the present invention is characterized in that a further spring is interconnected with the first spring by an interconnecting arrangement which when the first spring breaks moves into a disengagement position whereupon the further spring tends to hold the throttle in the Idle position with its entire spring force.

For the throttle in accordance with the present inventron care has been taken that the further spring is only fully effective, that is it only exerts all of its force against the actuating force of the operator when the first spring has been eliminated by fracture of the first spring. One to the solution of the problem in accordance w th the present invention the further spring can be so dimensioned that it exerts approximately the same moment upon the throttle or its shaft as does the first spring because this moment is only fully effective when the moment exerted by the first spring disappears due to fracture thereof.

Preferably, the arrangement is such that the first and the further spring are so connected to the connecting arrangement that the further spring moves the connectlng arrangement into the release position when the first spring fractures.

A particularly simple embodiment of the invention consists in that the connecting arrangement includes a two-armed swinging lever, one arm of which is maintamed in a rest position by a first spring forcing it against a stop while the other arm is formed as an end of the further spring to urge it against the throttle or a part rotating therewith by means of a hook which is released when the further spring swings the swinging lever from the rest into the release position. Accordingly, the further spring only rests against the throttle or a portion rotating therewith when the first spring has been eliminated whereupon the further spring has swung the swinging lever into the release position. The further spring may be arranged as a leg spring disposed on the swinging shaft of the throttle, the other end of the spring being fixed, for example, by connecting it to a projection of the intake manifold.

For a further embodiment of the invention the connecting arrangement includes also a two-armed swinging lever, at the arms of which the first and the further spring are connected in parallel.

While in the previously described embodiment the swinging lever is pulled by the first spring against a rigid stop or is pressed thereagainst, for the embodiment of the invention presently to be described the swinging lever is provided with a third spring disposed in the region between the connections of the first and the further spring to counteract one of these springs. The arrangement is such that when the swinging lever is moved into the release position, the third spring releases the swinging lever. This further or counter spring has the purpose and is so dimensioned with respect to the two other springs that during normal operation of the arrangement the resulting spring force of the three springs is opposite to the operating force which may, for example, be exerted by a pedal and is of such magnitude that it requires the normal operating force. However, as soon as the swinging lever has been swung into its release position, that is when the first spring has fractured the connection between the third spring and the swinging lever is automatically disengaged so that now the further spring is fully effective without the counterforce exerted by the third spring. The portion of the spring force which up to now was compensated by the force of the counterspring now takes the place of the first spring which has been eliminated. Because in the normal state of the arrangement both springs are partially operative the terms first spring and further spring may be exchanged. Only in case of damage the spring that is broken becomes the first spring according to the invention. At the same time the remaining spring is defined as the further spring.

The invention permits complete freedom in the arrangement of the springs. The first and the further springs may be extension or draw springs while the third spring may be a compression spring supporting the swinging lever. In this case there are three efficient and preferably parallel springs. On the other hand, for a further embodiment of the invention, all springs may be extension springs in which case the third spring is connected to the swinging lever by means of a hook connection which releases the swinging lever during swinging motion. Also, in this case the third spring causes a reduction of the forces exerted by the first spring and the further spring in a direction opposite the operating forces but only as long as both the first and the further spring are operative.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a portion of an internal combustion engine embodying the spring arrangement of the invention for the throttle;

FIG. 2 is a side elevational view similar to that of FIG. 1 but illustrating a second embodiment of the inven tion;

FIG. 3 is a partial view of the embodiment of the invention taken on line III III of FIG. 2;

FIG. 4 is a side elevational view of a portion of the apparatus of FIG. 2 in the release state, that is when one of springs is fractured;

FIG. 5 is a side elevational view similar to that of FIG. 1 but showing a third embodiment of the invention; and

FIG. 6 is a partial view taken on line VI VI of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings wherein like elements are shown by the same reference characters and particularly to FIG. 1, there is illustrated an internal combustion engine indicated at M and having air intake manifold or vacuum tube portions 1' and 1 connected to the engine cylinders. An upstream portion of the air intake manifold is shown at 1 having a throttle 2 disposed on a throttle shaft 3 on which the throttle 2 is arranged to rotate along with the shaft. A swinging lever 4 is connected with the throttle shaft 3 and rotates therewith. The operating force indicated schematically by the arrow 5 attacks the swinging lever 4 by means of a suitable connecting rod or ropes in order to open the throttle 2. These operating forces are exerted by means of the gas pedal.

As shown in FIG. 1 which illustrates a first embodiment of the invention, the first spring 6 extends between the swinging arm 4 on the one hand and a connecting arrangement on the other hand which includes as its essential element the two-armed swinging lever 7. The lever 7 is swingably disposed about a fixed swinging shaft 8 and is pulled by the force of the extension spring 6 in the normal state of the arrangement against a fixed stop 9. Within the range of the right arm of the swinging lever 7 as shown in FIG. 1 the lever has a recess or cutout 10 of generally hook shape. A connection which may, for example, consist of a wire 11 is connected to this hook which in turn is connected to the end 12 of the leg spring 13 which bears with its other end 14 against a fixed stop 15 which may be disposed at the intake manifold 1. This leg spring 13 surrounding the throttle shaft 3 in the operating state shown in the drawing is held by means of the connection 11 out of engagement with the throttle 2 or its swinging arm 4. However, as soon as the first spring 6 fractures the two-armed swinging lever 7 is swung by the action of the further spring 13 into its release position 7. Accordingly, the connection 11 slides out of the hook which now assumes the position 10 and the connection assumes a position indicated at 11. At the same time the end 12 of the further spring 13 rests against a stop at the swinging arm 4 as indicated at 12 so that the fu rther spring 1 3 tends to swing the swinging arm 4 of the throttle 2 into the idle position. This, however, is only possible when the operating force 5 permit such a swinging movement. One advantage of the arrangement according to the invention may be seen in that even after the first spring 6 has fractured, the car provided with the arrangement of the invention is in operating condition. In order to indicate to the driver that the first spring 6 has fractured it may be suitable to dimension the further spring 13 in such a manner that larger operating forces 5 are necessary.

In the embodiment of the invention illustrated in FIGS. 2-4 there is again used a two-armed swinging lever 20; however, a fixed stop corresponding to the stop 9 of the embodiment of the invention of FIG. 1 is missing. The swinging lever 20 is capable of swinging about a swinging shaft 21 which is held in the left end portion of the swinging lever 4 as shown in FIGS. 2 and 4. As shown particularly in FIG. 3, this swinging shaft 21 also serves for introducing the operating forces from the pedal (see arrow 5). In each of the two arms of the two-armed swinging lever 20 there is suspended the upper end of one of the two springs 22 and 23.

The lower ends of the two springs 22 and 23 are secured to a fixed element 27. In the following the spring 22 is referred to as the first apring and the spring 23 as the further spring in accordance with the invention. Between the two connecting points of the springs 22 and 23 the two-armed swinging lever 20 is provided with a vaulted bearing 24 for the correspondingly ball-shaped end 25 of the third spring 26 which in this embodiment of the invention is a compression spring. Accordingly, the third spring reduces the action of the two extension springs 22 and 23 with respect to the magnitude of the required operating force 5. The resulting spring force of the three springs 22, 23 and 26 is so selected that it is opposed to the operating force 5. Accordingly, it tends to swing the throttle into its idle position and the magnitude of the three springs is such that it has the desired value for opposing the operating force.

As soon as the first spring 22 fractures, the twoarmed swinging lever 20 is swung under the action of the further spring 23 about its swing shaft 21, whereby the swing lever 20 in view of the bearing 24, 25 of the third spring 26, disengages the third spring. The swinging lever 20-accordingly assumes the position shown in FIG. 4 so that now the further spring 23 acts with its full spring force upon the throttle 2 in view of the fact that the force of the third spring 26 has been eliminated.

The embodiment shown in FIGS. 5 and 6 is quite similar to that of FIGS. 2 and 4. Also in this embodiment there is provided a two-armed swinging lever 30, the swinging shaft 31 of which is journalled in the Swinging arm 4. Again there are provided two springs 32 and 33 which are disposed as extension springs and the upper ends of which are hooked respectively into one arm of the two-armed swinging lever 33. However, while in the embodiment of FIGS. 2-4 the swinging lever 20 is normally supported by a compression spring 26, in the embodiment of FIGS. 5 and 6 of the invention it is suspended by the third spring 34 which is also arranged as an extension spring. The third spring 34, as indicated in FIG. 5, is fixedly supported at its upper end at 35. The connection between the third spring 34 and the twoarmed swinging lever 30 takes place by means of a hook connection shown particularly in FIG. 6 which includes a first hook 36 at the two-armed swinging lever 30 and a second hook 37 at the lower end of the third spring 34. Because these hooks do not have lateral guides, a swinging movement of the two-armed swinging lever 30 which occurs when one of the springs 32 and 33 fractures, causes the hooks to slide off each other so that the connection of the swing lever 30 with the third spring 34 is disengaged. Accordingly, again only that one of the springs 32 and 33 is operative to rotate the throttle 2 which has remained in operation. When, for example, the spring 32 is eliminated which then is the first spring according to the invention, the further spring which is now spring 32 swings the swing lever 30 in a clockwise direction so that the spring 34 is disenaged. Thereupon the full spring force of the spring 33 is effective.

It will be apparent that the arrangement of the springs as extension and compression springs in the two embodiments of the invention described in connection with FIGS. 2-4 and FIGS. 5-6 may be exchanged.

What is claimed is:

l. Throttle control for internal combustion engines, particularly for an automobile having a throttle in an air intake manifold, comprising throttle means movable between an idle position and a plurality of operating positions;

a normally operative first spring connected to said throttle means and biasing the same to said idle position;

a further spring which is normally disconnected from said throttle means; and

means for operatively connecting said further spring to said throttle means only in the event of failure of said first spring, for said further spring to bias said throttle means to said idle position thereof.

2. Control as defined in claim 1, wherein said connecting means includes a two-armed swinging lever, one arm of said swinging lever being connected to said first spring to tend to rotate said swinging lever against a stop into its rest position, the other arm of said swinging lever being connected to one end of said further spring, the other end of said further spring resting against a fixed stop, said other arm of said swinging lever forming a hook which releases said one end of said further spring to act on said throttle when said further spring swings said swinging lever from its rest into its release position.

3. Control as defined in claim 1 wherein said further spring has a leg spring disposed on the swinging shaft of 6 said throttle means, the other end of said further lever being connected to a fixed part.

4. Control as defined in claim 1 wherein said connecting means includes a two-armed swinging lever having a first arm to which is connected said first spring and a second arm to which is connected said further spring, said first and further springs being connected in parallel and a third spring connected to a region of said swinging lever between the connection of said first and said further springs, said third spring acting opposite to said first and further springs, said third spring and its connection to said swinging lever being such that when said swinging lever is rotated into its release position,

- said third spring releases said swinging lever.

5. Control as defined in claim 4, wherein said first and said further springs are extension springs, and said third spring is a compression spring supporting said swinging lever.

6. Control as defined in claim 4, wherein all of said springs are extension springs, said third spring being connected to said swinging lever by a hook connection which is released during swinging motion of said swinging lever.

7. Throttle control for internal combustion engines, particularly for an automobile having a throttle disposed in an air intake manifold, comprising a throttle;

a first spring operatively connected to said throttle and normally tending to move said throttle into its idle position;

a normally inoperative furthr spring; and

a connecting arrangement for interconnecting said first and said further spring, said connecting arrangement including a two-armed swinging lever having one arm connected to said first spring to be pivotally biased thereby against a stop into its rest position, the other arm of said swinging lever being connected to one end of said further spring and the other end of said further spring resting against a fixed stop, said other arm of said swinging lever forming a hook which releases said one end of said further spring to act on said throttle when said further spring swings said swinging lever from its rest position into its release position.

=l =l =l l 

1. Throttle control fOr internal combustion engines, particularly for an automobile having a throttle in an air intake manifold, comprising throttle means movable between an idle position and a plurality of operating positions; a normally operative first spring connected to said throttle means and biasing the same to said idle position; a further spring which is normally disconnected from said throttle means; and means for operatively connecting said further spring to said throttle means only in the event of failure of said first spring, for said further spring to bias said throttle means to said idle position thereof.
 2. Control as defined in claim 1, wherein said connecting means includes a two-armed swinging lever, one arm of said swinging lever being connected to said first spring to tend to rotate said swinging lever against a stop into its rest position, the other arm of said swinging lever being connected to one end of said further spring, the other end of said further spring resting against a fixed stop, said other arm of said swinging lever forming a hook which releases said one end of said further spring to act on said throttle when said further spring swings said swinging lever from its rest into its release position.
 3. Control as defined in claim 1 wherein said further spring has a leg spring disposed on the swinging shaft of said throttle means, the other end of said further lever being connected to a fixed part.
 4. Control as defined in claim 1 wherein said connecting means includes a two-armed swinging lever having a first arm to which is connected said first spring and a second arm to which is connected said further spring, said first and further springs being connected in parallel and a third spring connected to a region of said swinging lever between the connection of said first and said further springs, said third spring acting opposite to said first and further springs, said third spring and its connection to said swinging lever being such that when said swinging lever is rotated into its release position, said third spring releases said swinging lever.
 5. Control as defined in claim 4, wherein said first and said further springs are extension springs, and said third spring is a compression spring supporting said swinging lever.
 6. Control as defined in claim 4, wherein all of said springs are extension springs, said third spring being connected to said swinging lever by a hook connection which is released during swinging motion of said swinging lever.
 7. Throttle control for internal combustion engines, particularly for an automobile having a throttle disposed in an air intake manifold, comprising a throttle; a first spring operatively connected to said throttle and normally tending to move said throttle into its idle position; a normally inoperative furthr spring; and a connecting arrangement for interconnecting said first and said further spring, said connecting arrangement including a two-armed swinging lever having one arm connected to said first spring to be pivotally biased thereby against a stop into its rest position, the other arm of said swinging lever being connected to one end of said further spring and the other end of said further spring resting against a fixed stop, said other arm of said swinging lever forming a hook which releases said one end of said further spring to act on said throttle when said further spring swings said swinging lever from its rest position into its release position. 